1. Field of the Invention
This invention is directed to a method for forming colored images on a differentiated background, by the application of thermal energy to an otherwise stable :coating of colloidal metastable metal particles.
2. Background of the Prior Art
In 1972, Defensive Publication T900,010 was published, describing the preparation of blue colloidal silver, having a relatively large particle diameter (about 300 A), which could be coated onto a surface, and immediately developed by the application of halide ions. Even the application of a skin surface, such as a fingertip, against the metastable silver particle coating is described as providing sufficient halide ions to form an image of the fingerprint.
However, formation of an image through the application of halide ions, using the unstable blue silver of the Defensive Publication, poses a number of obstacles and drawbacks. Thus, the resolution and sharpness of the image available using a halide ion is unsatisfactory for the provision of a yellow image having high density information and differentiation. Additionally, quantitative control of the halide ion, and application is a physically intensive process, that is not easily automated. Halide delivery from exposed and developed silver halide images involves controlled light exposure and a separate wet process. Given such impracticalities of image formation using a halide ion, the image formation process in Publication T900,010 is not practical for obtaining finely resolved images of commercial quality.
Accordingly, it remains an obJect of the art to provide a non photographic image formation system, which is capable of forming instant and stable highly resolved images on a differentiated colored background.